Deposition of high quality YBa2Cu3O7−δ thin films over large areas by pulsed laser ablation with substrate scanning

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Abstract
We describe the transport and structural properties of YBa2Cu3O7−δ thin films deposited by pulsed laser ablation with computer‐controlled substrate scanning. Films were deposited on LaAlO3 and SrTiO3 substrates covering a 2×3 cm area with thicknesses of 90 and 160 nm. The 90‐nm thick films exhibited a thickness variation of ±8%, Tco = 90.7 ± 0.5 K, Jc = 4.8 ± 0.2 × 106 A/cm2 at 77 K, and a surface resistance (corrected for finite thickness) at 75 GHz of 10–12 mΩ at 77 K. For the 160‐nm thick films, the thickness variation was Tco = 91.0 ± 0.3 K, Jc=5.4±0.4×106 A/cm2, and corrected surface resistance was 6–10 mΩ. X‐ray diffraction showed that the c‐axis mosaic in the films is closely related to that of the substrates and that the only in‐plane defects are due to the expected twinning in the a‐b plane of the film. The c‐axis lattice constants were 1.1688±0.0004 nm. The above properties showed a high degree of uniformity across the substrate area and between films from different deposition cycles. The surface resistance values add significantly to the body of results which show that the temperature‐scaled values for niobium can be equaled and perhaps surpassed by YBa2Cu3O7−δ.